The increased survival of children with Systemic Lupus Erythematosus (SLE) into adulthood has resulted in novel morbidities such as osteopenia and the associated increased risk of spontaneous vertebral compression fractures and fractures secondary to trauma related to sports and other normal childhood activities. Like other children with severe illness, these children are particularly susceptible to the development of osteopenia due to the limited window of time during childhood dedicated to achieving peak bone mass, and the critical role of peak bone mass in the future development of osteopenia. Additionally, individuals with SLE may be at particularly high risk for the development of osteoporosis due to their use of glucocorticoids, sunshine avoidance with possible vitamin D deficiency, renal disease with potential effect on vitamin D hydroxylation, and decreased activity due to severe illness and arthritis. Very few studies have been performed to evaluate bone mineral density (BMD) in children with SLE and thus neither the incidence nor the appropriate treatment is known. The proposed study will characterize the incidence and severity of osteopenia in pediatric SLE with particular attention to the bone age and sexual development of the child. Additionally, the study will begin the evaluate the clinical risk factors associated with osteopenia in this population. Identification of risk factors will ultimately contribute to the development of preventive and therapeutic interventions. The evaluation of BMD in the context of Tanner stage and bone age in this project may result in the development of bone age-specific treatment protocols for pediatric SLE. Furthermore, information gained from this research may have application to the study of osteopenia in other autoimmune disorders, such as rheumatoid arthritis; and to other patients receiving corticosteroids such as those with nephrotic syndrome and inflammatory bowel disease. The utilization of two densitometric techniques, Dual photon x-ray absorptiometry (DXA) and Single-energy quantitative computerized tomography (SEQCT) will permit us to address the current question of the most appropriate methodology for measuring bone mineral density in children.